When using culture specific attributes for properties connected to MediaData classes, such as our implementation of ImageData, the text that is added in the properties is not being handled as culture specific. Text saved on the Swedish site overrides text from the Norwegian site and vice versa.

Unfortunately, localizing media assets is not supported yet but the following workarounds should work in this case

https://gregwiechec.com/2015/07/localizable-media-assets/
https://www.patrickvankleef.com/2014/06/16/use-culture-specific-mediadata-properties/